The Mark-XXXVI Defense Gun commonly called the Mark 36 or just 36 was a slugthrower based defensive gun mounted on the Eshan Orbital ring system and used as defense guns on the Mephistopheles-type Bellator-class Star Battlecruiser. The weapon was a rotary cannon, which meant that it had multiple barrels that rotated. When a barrel holding a round fired a new one would rotate into place, while the on that fired had its spent cartridge discharged, and third barrel cooled, while a fourth had a new round loaded. This meant that the gun could fire continuously without the risk of overheating as the barrel had a chance to cool after each round.